import java.util.LinkedList;
import java.util.Queue;

public class BinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


/*    *//**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');

        A.left = B;
        A.right = C;
        B.left = D;
        C.left = E;
        C.right = F;
        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if(root == null){
            return ;
        }
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root == null){
            return ;
        }
        inOrder(root.left);
        System.out.print(root.val+" ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root == null){
            return ;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val+" ");
    }

    public static int nodeSize;

    /*
     * 获取树中节点的个数：遍历思路
     **/
    void size(TreeNode root) {
        if(root == null){
            return;
        }
        nodeSize++;
        size(root.left);
        size(root.right);
    }

    /*
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     **/
    int size2(TreeNode root) {
        if(root == null){
            return 0;
        }
        return size2(root.left)+ size2(root.right)+1;
    }



     //获取叶子节点的个数：遍历思路

    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if (root == null){
            return;
        }else if(root.left == null && root.right == null){
            leafSize++;
        }else {
            getLeafNodeCount1(root.left);
            getLeafNodeCount1(root.right);
        }
    }


     //获取叶子节点的个数：子问题

    int getLeafNodeCount2(TreeNode root) {
        if(root == null){
            return 0;
        } else if (root.right == null && root.left == null) {
            return 1;
        }
        return getLeafNodeCount2(root.right)+ getLeafNodeCount2(root.left);
    }


    //获取第K层节点的个数

    int getKLevelNodeCount(TreeNode root, int k) {
        if(root == null || k <= 0){
            return 0;
        }else if(k == 1){
            return  1;
        }
        return getKLevelNodeCount(root.left, k - 1) + getKLevelNodeCount(root.right, k - 1);
    }


     //获取二叉树的高度
     //时间复杂度：O(N)

    int getHeight(TreeNode root) {
        if(root == null){
            return 0;
        }
        return Math.max(getHeight(root.left),getHeight(root.right)) +1;

    }


    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if(root == null){
            return null;
        } else if (root.val == val) {
            return root;
        }
        TreeNode leftFind = find(root.left,val);
        if(leftFind != null){
            return leftFind;
        }
        TreeNode rightFind = find(root.right,val);
        return  rightFind;
    }

    //层序遍历
    void levelOrder(TreeNode root) {

    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        if(root == null){
            return true;
        }
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while(!queue.isEmpty()){
            TreeNode cur = queue.poll();
            if(cur != null){
                queue.offer(cur.left);
                queue.offer(cur.right);
            } else if (cur == null) {

                while (!queue.isEmpty()){
                    TreeNode c = queue.poll();
                    if(c != null){
                        return false;
                    }
                }
            }
        }
        return true;
    }

    public void siftUp(int child){
        int parent = (child - 1) / 2;
        while (parent >= 0){
            if(elem[parent] < elem[child]){
                int temp = elem[parent];
                elem[parent] = elem[child];
                elem[child] = temp;
                child = parent;
                parent = (parent - 1) / 2;
            }else {
                return;
            }
        }
    }
}